L11: Algae

algae

• photosynthetic protists who gained oxygenic photosynthesis via primary/secondary endosymbiosis

• responsible for 30% of oxygen

algal blooms

• rapid growth of algae due to increase in nutrients

• runoffs from factories

• caused by both algae and cyanobacteria

algal blooms dangers

• damages environment and its inhabitants

• water hypoxia through decomposition of dead algae

• produces toxins

• damaging gills

• increasing due to climate change

dinoflagellates

• unicellular algae

• half are chemoheterotrophs others are photoautotrophs/ mixotrophs

red tide

• photoautotrophic dinoflagellates contain carotenoids

• algal bloom of these cause red tides

haptophytes

mostly marine, unicellular photoautotrophs/ mixotrophs

haptophytes structure

• 2 flagella for motility

• haptonema for surface attachment and predation

• surface covered with small scales of polysaccharides

Emiliana hyxleyi

• hard, calcified scales

• accumulated on ocean floor to create cliffs of dover

stramenopiles

many members have fine, hairlike projections

diatoms

• unicellular, photoautotrophic stramenopile

• one of the most abundant photosynthetic organisms in oceans

• glass like cell wall made of silicon dioxide for protection and predation

diatoms and forensic limnology

• diatoms are well preserved due to their silica shell

• can be matched to a location if found on someone

brown algae

• seaweed

• multicellular, photoautotrophic stramenopile

• can get 60m tall

how is brown algae similar to plants

• blades - increase surface area (leaf like)

• stipe - support the blades (stem like)

• holdfast - anchor the alga (root like)

• plant like reproduction

draw sexual reproduction cycle in humans

h

alteration of generation

plants and some algae produce multicellular bodies in both diploid and haploid stages

draw alteration of generation cycle

h

what does it alternate between

• sporophyte - spore producing, diploid multicellular form

• gametophyte - gamete producing, haploid multicellular form

zoospores

• brown algae spores

• can move with flagella

• half develop into female gametophytes, half into male

archaeplastida

• direct ancestors of primary endosymbiosis

• source organisms of secondary endosymbiosis

green algae

• paraphyletic group missing plants

• 2 main groups: chlorophytes, charophytes

chlorophytes

sister group to the clade charophytes + plants

charophytes

• closest relative to land plants

• determined by molecular phylogeny of nuclear, mitochondrial, plastid DNA, morphological features

similarities between charophytes and plants

• synthesize cell wall using ring like protein structure

• flagellated sperm

• similar nuclear, mitochondrial and chloroplast DNA

• sporopollenin

sporopollenin in charophyte

• tough layer surrounding zygotes to prevent it from drying out

• eventually enabled them to live on land

sporopollenin in plants

encase plant spores